In the specific case of frozen composite food products, in order to operate on an industrial scale, it is necessary, in order to form the final product, for the said "combination" of two or more pre-selected components to take place after at least the main component has been frozen.
Thus, for example, in the case of pre-cooked pasta seasoned with a pre-selected sauce, the pre-cooked pasta is normally frozen and the individual pieces of pasta are then (ideally) sprinkled with the pre-selected seasoning (sauce) which thus simultaneously freezes thereon.
An ideal sauce/pasta combination is quite difficult to achieve since it is greatly hindered by the objective difficulty of breaking up the mass of pre-cooked and frozen products (the pasta) and by the rate at which the sprinkled component (the sauce) freezes in contact with the products.
The techniques used up to now for achieving the aforementioned object are based fundamentally on an operation known in Italian as "bassinatura", in which continuous mixing of the frozen products is associated with rolling of the products in the surface or upper layers on those of the underlying layers.
Although these techniques are widely used and, in some cases, are even satisfactory, they do not generally enable the sprinkled component to be distributed uniformly on the frozen component, above all, because of the substantial failure to break it up. In many cases, undesired lumps of product are even formed, because of the chemico-physical characteristics of the sprinkled component and because of its spontaneous freezing onto the frozen component.
A further problem of the prior art is connected with the structural and functional complexity of the apparatus used to produce the composite food products in question, its poor reliability in operation, and also the need to use skilled operators for constantly monitoring its operation.